Firefox can't load websites but other browsers can

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This article describes problems where Firefox cannot load websites, but other web browsers (such as Internet ExplorerSafariEpiphany on Gnome or Konqueror on KDE) can. When this happens, Firefox may show a Server not found or Unable to connect error message.

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Internet Security software blocking Firefox

If you were able to load websites until you updated Firefox or until your Internet security software was updated, reconfigured or a new one was added, your Internet security software (including firewalls, antivirus programs, anti-spyware programs, and more) is likely preventing Firefox from connecting to the Internet.

Note: Some Internet security programs can block Internet access even when they are in a "disabled" state.

In general, you should make sure your Internet security software is up-to-date and remove Firefox from your program's list of trusted or recognized programs, then add it back. For instructions on how to configure some programs, see the Configure firewalls so that Firefox can access the Internet article.

Firefox connection settings

If you connect to the Internet through a proxy server that is having connection problems, you will not be able to load websites. To check your connection settings in Firefox:

Click the menu button and choose Options.Preferences.

Select the Advanced panel.

Select the Network tab.

In the Connection section, click Settings….

Change your proxy settings:

If you don't connect to the Internet through a proxy (or don't know whether you connect through a proxy), select No Proxy.

Click the arrow next to Details to display the list of items that can be cleared.

Select both Cookies and Cache.

Click Clear Now.

Check for malware

If clearing your cookies and cache did not enable you to load the websites that did not work in Firefox, you should check your computer for malware. Certain types of malware are known to target Firefox and can prevent it from loading various websites:

If you have an antivirus or Internet security program, update its detections database and do a full scan of your system.